IF? That is a child’s game.
These claims started on twitter, speculation that grew, and in my opinion people talking authoritatively in ambiguous terms about what they were not sure happened. No one in authority, or a position to know has said "The U.S. seized servers in Germany that show the election was rigged". If it happened, there would be no reason not to say so directly, and hinting that it happened would confirm it to those who were involved if it was true.
Because if they existed and were seized, both sides would know and would be mutually aware of it. That would change both sides actions. If they exist, the President would have not reason not publicize it and put up files on the White House web page or give it all to Wikileaks. There is no advantage to playing internet mind games over this and too much at stake.